1. Field of the Invention
The present invention relates to an improved machine for the manufacture of texturized yarns by false-twist, and more particularly to a machine for processing of partially drawn or undrawn yarns either by the so-called "sequential draw-texturizing" technique or by the so-called "simultaneous draw-texturizing" technique.
2. Description of the Prior Art
Commonly assigned U.S. Pat. No. 4,051,650 describes a false-twist texturizing machine which presents reduced overall dimensions, particularly in height, and which, furthermore, provides a straight linear path for the yarn between the entry of the thermal treatment heater and the false-twist spindle.
Generally, the machine described in the aforesaid U.S. Pat. No. 4,051,650 includes a plurality of treatment positions, comprising in operational sequence:
a yarn supply device; PA1 a first yarn feeder; PA1 a heating device; PA1 a cooling zone for the heated yarn; PA1 a false-twist spindle; and PA1 a wind-up device;
and, when desired, the machine may further include a thermal setting device with a third yarn feeder situated immediately before the wind-up device. The machine of U.S. Pat. No. 4,051,650 comprises a central frame on either side of which are arranged symmetrically the treatment positions. Between the yarn supply and the wind-up zone, this machine defines a service zone for the personnel, with the first heater, the cooling zone and the point where the yarn enters the false-twist spindle being in substantially straight alignment and arranged at least in part above the service zone.
Advantageously, the first heater and the cooling zone are inclined with respect to the horizontal plane, and means are provided to guide the yarn from the first yarn feeder to the entry of the first heater. With a closed heater, as illustrated in U.S. Pat. No. 4,051,650, the guide means may comprise a J-shaped tube whose point of entry is situated proximate the first yarn feeder and which is connected to the heater entry.
The machine of U.S. Pat. No. 4,051,650 has proved satisfactory in that it permits a substantially straight yarn threadline in the heater and cooling zone while having the advantages of minimum overall dimensions and of allowing the operator to have easy access to the essential parts of the machine, particularly during the lacing-up operations.
However, it has been noticed that for certain applications, particularly when processing fine yarn counts, for example with polyamide counts between 12 and 44 decitex, yarn irregularities may occur between the spindle and the first yarn feeder.
As described in U.S. Pat. No. 3,772,869, a texturizing machine could include at the entry point of the heater a device for locking the inserted twist; but this leads to yarn launching problems, and furthermore, during normal operation, breakages occur at the level of the transfer-tail knots.
The present invention defines an improvement in false-twist texturizing machines of the type described in the aforesaid U.S. Pat. No. 4,051,650, which overcomes the aforesaid disadvantages while keeping the advantages of the straight linear threadline, the low height, and service facility for the operator.